I am trying to convert the below python code into java
def _convert_base10encoded_to_decompressed_array(base10encodedstring) -> None:
bytes_array = base10encodedstring.to_bytes(5000, 'big').lstrip(b'\x00')
self.decompressed_array = zlib.decompress(bytes_array, 16+zlib.MAX_WBITS)
the java code
public void convertBase10EncodedToDecompressedArray(String base10encodedstring) throws Exception {
// Step 1: Convert base10encodedString to a BigInteger
BigInteger bigIntValue = new BigInteger(this.base10encodedstring);
// Step 2: Convert BigInteger to a byte array in big-endian order
byte[] bigIntBytes = bigIntValue.toByteArray();
byte[] bytesArray = new byte[5000]; // Create a 5000-byte array (zero-initialized)
// Copy the BigInteger's byte array to the end of the 5000-byte array to mimic Python's behavior
int copyStart = 5000 - bigIntBytes.length;
System.arraycopy(bigIntBytes, 0, bytesArray, copyStart, bigIntBytes.length);
// Step 3: Remove leading zeros to mimic Python's lstrip(b'\x00')
int nonZeroIndex = 0;
while (nonZeroIndex < bytesArray.length && bytesArray[nonZeroIndex] == 0) {
nonZeroIndex++;
}
byte[] trimmedBytesArray = new byte[bytesArray.length - nonZeroIndex];
System.arraycopy(bytesArray, nonZeroIndex, trimmedBytesArray, 0, trimmedBytesArray.length);
// Step 4: Decompress the byte array using Inflater with a header flag
Inflater inflater = new Inflater(true); // `true` for handling zlib/gzip headers
inflater.setInput(trimmedBytesArray);
// Prepare output buffer for decompressed data
byte[] output = new byte[10000]; // Adjust size as needed for decompression
int decompressedDataLength;
try {
decompressedDataLength = inflater.inflate(output);
inflater.end();
} catch (DataFormatException e) {
throw new Exception("Decompression failed: " + e.getMessage(), e);
}
// Store the decompressed data in decompressedArray
decompressedArray = new byte[decompressedDataLength];
System.arraycopy(output, 0, decompressedArray, 0, decompressedDataLength);
}
The java code seems to be not doing the conversion same as python and erroring out:
Decompression failed: invalid block type
java.lang.Exception: Decompression failed: invalid block type
Here is the sample data that can be used for testing 119042439702058329181580366339137026727847632133400914982925157100269769134885477532825542376007928853630543405886877144858046550370019093958674847428579819304849334337536
this works well with python but fails in Java, generated it using the logic
sample_data = b"This is a sample data for testing zlib decompression."
# Compress the data using gzip
buf = io.BytesIO()
with gzip.GzipFile(fileobj=buf, mode='wb') as f:
f.write(sample_data)
compressed_data = buf.getvalue()
# Convert the compressed data to a base-10 integer
compressed_int = int.from_bytes(compressed_data, 'big')
You can use GZIPInputStream and remove the need for Inflater. This works fine:
private byte[] decompressedArray;
public void convertBase10EncodedToDecompressedArray(String base10encodedstring) throws Exception {
// Step 1: Convert base10encodedString to a BigInteger
BigInteger bigIntValue = new BigInteger(base10encodedstring);
// Step 2: Convert BigInteger to a byte array in big-endian order
byte[] bigIntBytes = bigIntValue.toByteArray();
byte[] bytesArray = new byte[5000]; // Create a 5000-byte array (zero-initialized)
// Copy the BigInteger's byte array to the end of the 5000-byte array
int copyStart = 5000 - bigIntBytes.length;
System.arraycopy(bigIntBytes, 0, bytesArray, copyStart, bigIntBytes.length);
// Step 3: Remove leading zeros
int nonZeroIndex = 0;
while (nonZeroIndex < bytesArray.length && bytesArray[nonZeroIndex] == 0) {
nonZeroIndex++;
}
byte[] trimmedBytesArray = Arrays.copyOfRange(bytesArray, nonZeroIndex, bytesArray.length);
// Step 4: Use GZIPInputStream for decompression
try (ByteArrayInputStream bis = new ByteArrayInputStream(trimmedBytesArray);
GZIPInputStream gzis = new GZIPInputStream(bis);
ByteArrayOutputStream bos = new ByteArrayOutputStream()) {
byte[] buffer = new byte[1024];
int len;
while ((len = gzis.read(buffer)) > 0) {
bos.write(buffer, 0, len);
}
// Store the decompressed data
decompressedArray = bos.toByteArray();
// Heres output for testing
System.out.println("Decompressed content: " + new String(decompressedArray));
}
}